Gas flushable tray

ABSTRACT

A food tray for use in a modified atmosphere package is provided by the present invention. The tray includes product area for holding food items, which may be specifically shaped for holding particular types of items, and at least 25% void area that does not hold any product due to the shape of the tray. The tray has air vents that facilitate gas flushing of the void area during packaging of the tray, wherein the air vents may also provide communication between the product area and void area. In addition, the air vents are not visible when food items are placed in the product area. The tray may be made of a single piece of folded material, wherein the folds form the void area.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to modified atmosphere packaging, and morespecifically, to a food tray design that facilitates more efficient gasflushing.

2. Description of Related Art

Maximizing the shelf life of packaged foods requires the removal ofparticular gasses from the sealed packaging. In particular, oxygen cancause fats to become rancid. This is especially true of unsaturatedcooking oils, which are often used in baked and fried food products. Itis also well known that oxygen contributes to staling of food products.To extend shelf life, many food packages are flushed with nitrogen justbefore the package is sealed. Because nitrogen is an inert gas, it doesnot react with foodstuff, thus preventing or significantly reducingoxidation and staling of the food product in the sealed package andotherwise extending the shelf life of the product.

The efficiency of nitrogen flushing depends on how much oxygen and otherreactive gases are removed from the packaging before it is sealed. Thisdepends on several factors, including the contents of the package. Forexample, potato and tortilla chips are typically packages in a loose orstacked manner. Flexible film bags are used for loose fill packaging, inwhich the film is formed into an open-ended bag and the food product(e.g., potato chips) is simply dropped or poured in. Before the bag issealed, it is flooded with nitrogen to flush out any remaining air inspace not occupied by the food.

Stacked products are typically packaged in non-flexible containers. Thefood items have a standard shape, which allows them to be uniformlystacked on top of each other, forming a column. The non-flexiblecontainer helps maintain the orderly stack. When the stacked food itemsare placed in the container, there is a small space between the food andthe sides of the container, which is flushed with nitrogen gas justbefore the container is sealed.

The introduction of food trays into food packaging creates problems forefficient gas flushing, because the shape of the tray might create“void” areas that are not used for holding food. These void areas cantrap air and impair the ability to efficiently flush oxygen and otherreactive gases from the packaging.

Therefore, it would be desirable to have a method for increasing theefficiency of gas flow throughout food packages containing trays duringthe nitrogen flushing process just before packaging.

SUMMARY OF THE INVENTION

The present invention provides a food tray for use in a modifiedatmosphere package. The tray includes product area for holding fooditems, which may be specifically shaped for holding particular types ofitems, and at least 25% void area that does not hold any product due tothe shape of the tray. The tray has air vents that facilitate gasflushing of the void area during packaging of the tray, wherein the airvents may also provide communication between the product area and voidarea. In addition, the air vents are not visible when food items areplaced in the product area. The tray may be made of a single piece offolded material, wherein the folds form the void area.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself, however, as well asa preferred mode of use, further objectives and advantages thereof, willbe best understood by reference to the following detailed description ofillustrative embodiments when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 depicts a side view schematic diagram illustrating a nitrogenflushing system in which the present invention can be implemented;

FIG. 2 is a plan view of an unfolded paperboard tray used for holdingpackaged food items in accordance with the present invention;

FIG. 3 depicts a perspective view of one embodiment of a foldedpaperboard tray for holding packaged food items in accordance with thepresent invention;

FIG. 4 depicts an end view, cross section diagram illustrating theassembled tray in accordance with the present invention;

FIG. 5 depicts a perspective view illustrating one embodiment of thefolded paperboard tray containing food items; and

FIG. 6 is a plan view of an unfolded paperboard tray used for holdingpackaged food items in accordance with an alternate embodiment of thepresent invention.

DETAILED DESCRIPTION

Referring now to the figures, FIG. 1 depicts a side view diagramillustrating a nitrogen flushing system in which the present inventioncan be implemented. In order to maximize the shelf life of packagedfoods, reactive gases such as oxygen need to be flushed from foodcontainers just before packaging. Nitrogen is the preferred flushing gasas it is inert and will not react with the food while inside thepackaging for extended periods. The example nitrogen flushing systemillustrated in FIG. 1 is designed specifically for food products thatare contained in special trays that are included in the final package.

Two trays 106, 107 containing the food product (deposited in an earlierstep, not pictured) and are moved along from right to left by twoin-feed chain lugs 108, 109. The trays 106, 107 pass through an enclosedtunnel 103 that is nitrogen flushed by overhead gas rails 104 emittingstreams of nitrogen gas 105. As explained above, nitrogen is used toflush other gases, such as oxygen, from the food trays 106, 107 beforepackaging.

The trays 106, 107 briefly leave the tunnel before entering a film tube102 on a horizontal flow wrapper. The film 102 is unwound from a roll101 and wrapped around the first tray 106 and sealed on the bottom toform a tube. After the first tray 106 is completely wrapped, the filmtube 102 is sealed at the ends to form the final package. As the firsttray 106 is moving from the nitrogen-flushed tunnel 103 into the filmtube 102, the film tube is flushed with nitrogen gas from below by meansof a gas tube called a nitrogen “lance” 110.

In many packaging systems, the nitrogen lance 110 is the primary meansby which packaging is flushed. The enclosed nitrogen flushing tunnel 103is often a non-standard add on that is only used when necessary fordifficult flushing applications.

FIG. 2 is a plan view of an unfolded paperboard tray used for holdingpackaged food items in accordance with the present invention. FIG. 3 isa perspective view illustrating the paperboard tray folded together,ready to hold the food product. The tray 200 includes a bottom section220 and folding sections 201-205 that fold together to form the side oftriangular rows 210, 211 in the middle of the tray 200, as depicted inthe perspective view picture in FIG. 3.

Referring to FIG. 4, an end view, cross section diagram illustrating theassembled tray 200 is depicted in accordance with the present invention.The end view in FIG. 4 clearly illustrates the spaces created when thefolding sections 201-205 are folded together as shown in FIGS. 3 and 4.The assembled tray 200 can be divided into product area and “void” area.The triangular rows 210, 211 represent the product area, which is thevolume of the tray 200 that is specifically dedicated to holding thefood items placed in the tray 200 (shown in FIG. 5). The void area,comprising spaces 401-403 beneath the folded sections 201-205,represents the volume of the tray 200 that does not hold food items dueto the shape of the tray and product area. In the present embodiment,the void area accounts for at least 25% of the volume of the tray 200.

The void areas 401-403 have the potential to trap air that will not beeffectively removed during the nitrogen flushing process. If thenitrogen gas cannot efficiently flush these air pockets, air andreactive gases may remain in the final package, reducing the shelf lifeof the product. To allow for more efficient gas flow through the voidareas 401-403, venting holes 230 are placed in the folding innersections 201-205. These holes provide communication between the productarea in rows 210, 211 and the void areas 401-403. This communicationallows for more thorough flushing of oxygen and other reactive gasesfrom the void areas 401-403 just before packaging.

FIG. 5 illustrates the folded paperboard tray 200 containing food items.In the example depicted, the tray 200 is filled with triangular tortillachips 500. The triangular shape of rows 210, 211 illustrated in FIGS. 3and 4, are designed to hold the triangular tortilla chips 500 in orderedrows. Though the venting holes 230 are not seen when the tray 200 isfilled with the chips 500, they will still allow efficient gas flow andnitrogen flushing. This is necessary, as the chips 500 must be loadedinto the tray 200 before nitrogen flushing. It should be pointed outthat the shape of the product space may vary, depending on the shape ofthe food product held in the tray 200.

FIG. 6 is a plan view of an unfolded paperboard tray used for holdingpackaged food items in accordance with an alternate embodiment of thepresent invention. The tray 600 depicted in FIG. 6 has venting holes630, similar to the tray 200 depicted in FIGS. 2-5. However, tray 600has the additional feature of venting slots 610 in the bottom surface620. These additional bottom, venting slots 610 allow for even greatergas flow and nitrogen flushing than the previous tray design 200. Thealternate tray design 600 is better suited for larger scale productionand packaging, in which the tray 600 would move through the nitrogenflushing chamber more quickly and would therefore require greater gasflow to ensure adequate nitrogen flushing within a shorter period oftime.

The present invention can also be applied to other types of tray designsand is not limited to the single-piece, folded paperboard tray exampledescribed above. For example, the tray in question might be amulti-piece paperboard tray, a formed paperboard tray, or a plastictray. Any one of these alternate tray designs can utilize air vents tofacilitate nitrogen flushing of void space in modified atmospherepackages.

In addition to improving gas flushing and shelf life, the presentinvention also has the advantage of reducing the need for additionalnitrogen flushing systems such as enclosed flushing tunnel 103 describedabove. Having a more efficiently vented container may allow adequatenitrogen flushing with a lance only.

While the invention has been particularly shown and described withreference to a preferred embodiment, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.

1. A food tray for use in a modified atmosphere package, the traycomprising: product area for holding food items; at least 25% void area;and at least one air vent that facilitates gas flushing of the void areaduring packaging of the tray, and wherein the air vent is not visiblewhen food items are placed in the product area.
 2. The tray according toclaim 1, wherein the tray is made of a single piece of folded material,and wherein the folds form the void area.
 3. The tray according to claim1, wherein the tray is made of paperboard.
 4. The tray according toclaim 1, wherein the tray is made of plastic.
 5. The tray according toclaim 1, wherein the product space is specially shaped to hold fooditems of a particular shape.
 6. The tray according to claim 1, whereinthe air vent provides communication between the product area and voidarea.
 7. The tray according to claim 1, wherein the at least one airvent is a plurality of air vents.